Mercury-vapor device



J. FORCE MERCURY VAPOR DEVICE Filed July 11. 1922 m H 3 m OF T m m a t m A .ma s n H O Patented Nov. 10, v 1925.

UNITED STATES PATENT O 1,560,936 FFJICE.

, JONATHAN FORCE, or LIVINGSTON, NEW JERSEY, Assreuon 'IO GENERAL ELECTRIC COMIANY, A CORPORATION OF NEW YORK.

MERCURY-VAPOR DEVICE.

To all LLILO'IIt it may concern:

Be "it known that I, JONATHAN Force, a citizen of the United .States, residing at Livingston, county of Essex, State of New Jersey, have invented certain new and useful Improvements in Mercury-Vapor Devices, of which the following is a specification. J

The present invention relates to mercury vapor devices, as for example, electric lamps ,or' the like, containing a'body of mercury in a sealed bulb, and it is the object of my invention toprevent the deposition of a film of mercurous material on the interior surface of these devices.

In mercury vapor devices, such, for e'X-' ample, as lamps containing an incandescent filament, or are electrodes of refractory metal operating at incandescence in mercury vapor, a metallic coating or film is deposited under some conditions on the glass bulb which is substantially-opaque to light, and, therefore, renders the lamp inefficient, or entirely inoperative. This coating consists largely of mercury with which various im purities may be mixed 7 In accordance with my present invention the formation of the light obscuringefilm on the bulb of mercury vapor devices is avoided by introducing into the bulb a material which will prevent apparently by a scouring action the formation of the mercurous film on the bulb. Although I may use for this purpose finely. divided materials, such as metallic tungsten, which remain intact under the operating conditions Within the bulb, I find that oxygenoug materials are particu larly eflicient.

The accompanying drawings illustrate two types of mercury'vapor devices to which mylnvention is applicable, but. I wish it to be;

' Application filedJuly 11,

1922 Serial No. 574,239.

with the main container through a restricted passage 3. In the part of the main container 1 are electrodes 4, 5, consisting of a suitable refractory metal, preferably tungsten, carried by stems 6, 7, also consisting of refractory metaland being smaller in cross section than the electrodes. These in turn are connected to conductors 8, 9, which are sealed into the bulb 1 in the usual manner. The bulb also contains a quantity of mercury 10, and preferably also a fixed gas whichis inert with respect to the electrodes 4, 5, at operatin g temperatures; for example, argon or nitrogen. If argon is used the pressure of the gas filling should be from 3 cm. to 10 cm. of mercury when the lamp is at room temperature. lVhen the are has been started, the heat radiated from the arc and incandescentelectrodes vaporizes some of the mercury and the mercury vapor eventually survent proper concentration and operation of the are at the electrodes, and should not be so high as to cause the electrodes to unduly waste away by electrical disintegration. The

exact limits of pressure can only be indicated in a general-manner as it will vary somewhat with the gas used, the particular size. construction, and in general, geometrical relations of the parts of each lamp. If the pressure is too low there will be a glow on the electrodes and lead wires. instead of an arc confined to the electrodes, while if the pressure is too high then highenvoltage is required to strike thearc.

Under the most favorable operating conditionsthere is a marked tendency to form the mirror-like film of mercury, or amalgam, on the bulb already mentioned above, Although the exact nature of this opaque film has not been clearly determined, it has the appearance of an amalgam-like mixture of finely dlvlded metal and mercury. lVhatcharacter of the lamp. I might say that (iii I have introduced into the bulb with success about one gram of fine tungsten powder obtamed by reducing tungstlc oxlde with hydrogen. When using silica I have added about one gram of silica of about the fineness of powdered sugar. This material is introduced through a tubulature before the lamp is exhausted, the tubulature being finally sealed off in the wel known way.

In my opinion the finely divided material which remains intact during the operation of the lamp, such as tungsten or silica, prevents the formation of the mercury film by a scouring action, the particles of tungsten or silica being swept over the tube walls by a mercury vapor blast emanating from the are. When using oxygenous compounds in the lamp there is also apparently a chemical action, or possibly the combination of a chemical and mechanical action, as a bluish film forms on the bulb and apparently the presence of this film prevents the adherence of the mercury or amalgam on the glass.

My invention is also applicable to the incandescent filament lamp shown in Fig. 2,

which comprises an elongated container or bulb 11, into the top of which are sealed conductors 12, 13 through a stem 14 in the usual manner. These conductors project in to the spherical chamber formed at the bottom of the container by a constriction in the container walls at 15. A coiled filament 16 is joined to the ends of the conductors 12, 13. This filament 16 is of a size and construction adapted to operate at high efficiency in an inert gas, as described in Langmuir Patent 1,246,118, of November 13, 1917. The bulb 11 also contains a quantity of mercury 17 and an. inert gas, such as argon or nitrogen, which is at a pressure high enough to enable the filament 16 to operate at high lighting efliciency, as described in the above Langmuir patent. During operation the mercury in the bulb is volatilized by the heat fromthe incandescent fila ment and as in the lamp described in Fig. 1, displaces the fixed gas in the part of the container surrounding the incandescent body.

Plating of an'opaque filament of mercury or the like in incandescent lamps of the type shown in Fig. 2, may be prevented in accordancewith my invention as above described. In the case of this class of lamps, "I prefer to introduce a small amount of oxygenous material such as mercury oxide, or to oxidize the filament slightly, for ex- In the case of any of the devices to which my invention is applicable and in the case of all the modifications of my invention, care should be exercisednot to add'too much of the anti-plating material as otherwise a discoloration of the bulb may be caused by the material itself; for example, the addition of too much silica will produce a grayish discoloration of the bulb, while the addition of too much oxygenous material produces an almost opaque bluish film on the glass.

hat I claim as new and desire to secure by Letters Patent of the United States, is

1. A device comprising a receptacle containing mercury and operating at a sulficiently hightemperature to cause said mercury to be vaporized, and oxygenous material in said receptacle acting upon the interior surface of said receptacle for preventing the formation of a film of mercury thereon during the operation of said device.

2. an electric device comprising the combination. of a sealed container, a body of mercury therein, means within said container whereby sufiicient heat is developed to vaporize mercury in appreciable amounts, and means within said container for liberating oxygen in amounts insufficient to affeet the electrical characteristics of said device but effective to modify surface condition of said container so that the formation of opaque mercury films on the walls of said container will be prevented.

3. An electric device comprising the combination of a bulb, an incandescent body therein adapted to operate at incandescence, a quantity of-mercury sufficient in amount to surround said body in a vapor during operation of the device, and an oxygenous compound of mercury in said bulb whereby the formation of an adherent of mercury on the wall of said bulb is prevented.

' 4. An electric lamp comprising the combination of a sealed glass bulb, a refractory body therein constructed to operate at incandescence, a quantity of mercury and means for producing on the inner surface of said bulb a layer of oxygenous material so'thin as to bewithout appreciable effect on the transparency of said bulb but effective to prevent a deposit of mercury thereon;

b In witness whereof, I have hereunto set my hand this 7th day of July 1922.

JONATHAN ronon. 

